WO2020007605A1 - Method and device for diamond synthesis by cvd - Google Patents

Method and device for diamond synthesis by cvd Download PDF

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Publication number
WO2020007605A1
WO2020007605A1 PCT/EP2019/066079 EP2019066079W WO2020007605A1 WO 2020007605 A1 WO2020007605 A1 WO 2020007605A1 EP 2019066079 W EP2019066079 W EP 2019066079W WO 2020007605 A1 WO2020007605 A1 WO 2020007605A1
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Prior art keywords
substrate
plasma
diamond
electrodes
chamber
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PCT/EP2019/066079
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French (fr)
Inventor
Horacio Tellez Oliva
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Diarotech
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Publication date
Application filed by Diarotech filed Critical Diarotech
Priority to JP2021521888A priority Critical patent/JP2021530625A/en
Priority to EP19730385.2A priority patent/EP3818189A1/en
Priority to US17/257,766 priority patent/US20210172060A1/en
Priority to CN201980044830.5A priority patent/CN112384640A/en
Publication of WO2020007605A1 publication Critical patent/WO2020007605A1/en

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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/26—Deposition of carbon only
    • C23C16/27—Diamond only
    • C23C16/272—Diamond only using DC, AC or RF discharges
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
    • C23C16/503—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using dc or ac discharges
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
    • C23C16/505—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using radio frequency discharges
    • C23C16/509—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using radio frequency discharges using internal electrodes
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
    • C23C16/517—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using a combination of discharges covered by two or more of groups C23C16/503 - C23C16/515
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32018—Glow discharge
    • H01J37/32027—DC powered
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32018—Glow discharge
    • H01J37/32036—AC powered
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32082—Radio frequency generated discharge
    • H01J37/32091—Radio frequency generated discharge the radio frequency energy being capacitively coupled to the plasma
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32431—Constructional details of the reactor
    • H01J37/3244—Gas supply means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32431—Constructional details of the reactor
    • H01J37/3266—Magnetic control means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/32—Processing objects by plasma generation
    • H01J2237/33—Processing objects by plasma generation characterised by the type of processing
    • H01J2237/332—Coating
    • H01J2237/3321—CVD [Chemical Vapor Deposition]

Definitions

  • the invention relates to the field of diamond synthesis or any other allotropic form of carbon by chemical vapor deposition.
  • Carbon is a material having several allotropic forms, naturally in the solid state on earth, which are amorphous carbon and three crystallized forms, graphite, diamond and lonsdaleite.
  • the diamond consists mainly of sp 3 hybridized carbon atoms while the graphite consists mainly of sp 2 hybridized carbon.
  • Other allotropic forms exist, in a synthetic state, such as DLC.
  • Diamond is a material with a unique combination of properties, such as resistance to wear, thermal conductivity or electrical insulation, which are very interesting for many technical applications.
  • the rarity and the price of natural diamonds make its use on a large scale impossible and confine it to luxury jewelry.
  • methods of diamond synthesis have been developed, in the hope of facilitating access to this material on a larger scale for technical applications.
  • DLC or “Diamond Like Carbon” is also an interesting material, differentiating from diamond by a proportion of sp 2 hybridization carbon, up to 60%, in sp 3 hybridization carbon.
  • the method of choice for the synthesis of thin diamond layers or DLC on a substrate is chemical vapor deposition or CVD (Chemical vapor deposition) at low pressure.
  • CVD Chemical vapor deposition
  • the diamond is deposited in crystalline form on a substrate placed in a chamber into which a gas carrying carbon atoms is introduced which is transformed into plasma by an energy source.
  • the invention relates first of all to a method of diamond synthesis, in a vapor deposition chamber and on a synthesis substrate, between two plasma generation electrodes, according to which:
  • a gas carrying carbon atoms is introduced into the chamber and a plasma is created near the substrate to generate reactive carbon atoms,
  • the invention also relates to a method of diamond synthesis, in a vapor deposition chamber (1) and on a synthesis substrate (5), between two electrodes (4, 5) for generating plasma, according to which:
  • a gas carrying carbon atoms is introduced into the chamber (1) and a plasma (28) is created near the substrate to generate reactive carbon atoms, process characterized by the fact that the plasma is created by applying, between the two electrodes, a direct current (DC) (6) and an alternating current at radio frequency (RF) (46).
  • DC direct current
  • RF radio frequency
  • the invention also relates, finally, to a method of diamond synthesis, in a vapor deposition chamber (1) and on a synthesis substrate (5), between two electrodes (4, 5) for generating plasma, according to which :
  • a gas carrying carbon atoms is introduced into the chamber (1) and a plasma (28) is created near the substrate to generate reactive carbon atoms,
  • diamond here is meant, and in the following description, all allotropic forms containing carbon in the sp 3 hybridization state, such as in particular diamond, in all its crystalline forms or DLC.
  • the reactive carbon atoms are typically carbon atoms in "activated" form, that is to say radical or ionic.
  • This expression also designates here carbonaceous molecules in an activated form, that is to say radical or ionic.
  • Compressing the plasma consists of guiding, or focusing, the reactive plasma species, such as the radicals and the ions produced between the electrodes, in a restricted region between the two electrodes in order to increase their concentration and, consequently, the probability of reaction shocks between radicals.
  • the increase in the number of shocks also makes it possible to generate UVC, or even infrared, photons which themselves make it possible to generate additional reactive atoms.
  • the combination of these effects makes it possible to considerably improve the speed of deposition of diamond on the substrate.
  • the electrodes between which the plasma is generated are supplied by a source of direct current (DC).
  • DC direct current
  • This energy source is effective in starting the diamond deposit.
  • the thickness of the layer formed becomes substantial, for example from 25-30 ⁇ m, at the temperature prevailing in the chamber, for example example between 300 and 1600 ° C, the diamond layer becomes an electrical insulator sufficient to significantly reduce the passage of energy between the electrodes and therefore decrease the diamond synthesis speed.
  • the applicant proposes a hybridization of the generation of energy and to combine the source of direct current (DC) with a current source by radiofrequencies (RF) and thus to create the plasma by application, between the two electrodes , direct current and alternating current at radio frequency (RF).
  • the direct current (DC) source can be permanent or chopped.
  • the DC / RF ratio can be adjustable during the synthesis, in particular as a function of the thickness of diamond already synthesized, so that the speed of diamond deposition remains constant.
  • the reactive carbon atoms in the plasma, it is possible to apply, near the substrate, a magnetic field.
  • the reactive atoms instead of following a direct trajectory between the electrodes, acquire in addition a movement of loop, or of helical tendency.
  • the reactive atoms thus travel a longer path and gain more speed, increasing the probability of collisions, generating the C-C sp3 hybridization bonds characteristic of diamonds, and therefore the speed of synthesis. This also helps to avoid arcs and holes in the diamond layer or film formed.
  • the plaintiff does not intend to limit the scope of its request to diamond synthesis.
  • the process of the invention can benefit any other material which can be synthesized by chemical vapor deposition, such as, for example, Si-Ge type semiconductors from a silicon-bearing gas and a germanium-bearing gas, or silicon oxides or nitrides.
  • the present invention first relates to the methods of claims 1-3.
  • the invention is not limited here to pure diamond, but can also be applied to doping diamond.
  • the diamond can be doped with boron; then introduced into the chamber, in addition to the gas carrying carbon atoms, a boron-carrying gas such as trimethylborane, boron trichloride or diborane.
  • Diamond can also be doped with nitrogen; is then introduced into the chamber, in addition to the gas carrying carbon atoms, a nitrogen-bearing gas such as dinitrogen, ammonia or methyl amine.
  • the invention also relates to a vapor deposition chamber, provided with a gas inlet and a gas outlet, and inside which are arranged two electrodes for generating plasma connected to a direct current (DC) source, characterized in that plasma compression means are provided between the two electrodes.
  • DC direct current
  • the two electrodes are also connected to a source of alternating current at radio frequency (RF).
  • RF radio frequency
  • the two electrodes are an anode and a cathode, the cathode forming a diamond deposition substrate.
  • Figure 2 schematically illustrates a vapor deposition chamber according to the invention
  • FIG. 3 is a perspective view of the electrodes and of the grid of FIG. 2.
  • a vapor deposition chamber 1 comprises an inlet 2 for gas, an outlet 3 for depressurization, electrodes, an anode 4 and a substrate 5 forming a cathode, connected to the terminals of a DC power supply 6, the circuit being connected to earth 7.
  • a gas carrying carbon atoms for example methane or ethane
  • the pressure in chamber 1 is reduced by applying a vacuum to the output 3 and a voltage is applied between the electrodes 4 and 5.
  • the molecules of the gas carrying carbon atoms are activated to form a plasma in a large volume 8.
  • the volume 8 of plasma extends beyond the area strictly between the electrodes.
  • the energy applied between the electrodes has the particular effect of dissociating certain bonds, such as for example C-H bonds, thus generating reactive species, such as for example carbon and hydrogen radicals.
  • reactive species such as for example carbon and hydrogen radicals.
  • These radicals can then either reassociate themselves with hydrogen radicals, or with other carbon radicals, thus leading to the formation of a CC bond, the hydrogen radicals can also associate with each other to form hydrogen gas which can be evacuated from the room by exit 3.
  • the energy of the CC bond being weaker than that of the CH bond, the reaction equilibrium is thus shifted towards the gradual replacement of all the CH bonds by CC bonds, that is to say the diamond formation.
  • the substrate may also contain species which make it possible to initiate, on contact, the formation of CC bonds.
  • Free radicals are an unstable species with a very long life in a gaseous medium. same if the formation of a molecular bond starting from the pendant bond of the radical is very energetically favorable it requires a shock to three bodies in order to allow the conservation of the momentum. It is therefore a very rare phenomenon. It is quite different on the surface, a gas radical associates easily with a radical center of the surface, because the phonons can then ensure the conservation of the momentum.
  • a sample holder can be placed on the substrate in order to give specific dimensions to the deposit, or to avoid deposit directly on the electrode.
  • the probability of collisions between reactive carbon atoms is directly proportional to the density of the atoms of these reactive carbon atoms in zone 8, which is itself linked to the energy applied between the two electrodes 4 and 5.
  • the electrodes 4 and 5 are here parallel disks whose centers are placed along an axis AA '.
  • the grid 20 is connected to a source of direct current.
  • the electrode 4 could have other forms, such as for example being made up of a single or of a set of points with a spherical end directed along the axis AA ′.
  • the electrode 4 can have a concave, convex or flat shape
  • the chamber 1 is placed under low pressure (pressure below atmospheric pressure) of gas carrying carbon atoms, by opening the gas inlet 2 and applying a vacuum at the outlet 3.
  • Direct current is applied between electrodes 4 and 5, generating a plasma of reactive carbon atoms between the electrodes.
  • a direct current is applied to the grid 20 in order to create around the cylinder which it defines, an electric field having the effect of orienting the reactive carbon atoms of the plasma in a zone 28 defined between the electrodes 4 and 5 and limited in width by the interior of the cylinder formed by the grid 20.
  • Diamond is gradually deposited on the substrate 5, in a homogeneous layer. For the same energy applied between the electrodes 4 and 5 between the devices of FIGS.
  • the plasma extension zone is reduced in the presence grid 20, the plasma is compressed, thereby increasing the density of the reactive carbon atoms.
  • the probability of collisions between reactive carbon atoms and with the surface is thus increased, which makes it possible to increase the speed of formation and deposition of diamond on the substrate, or optionally on a sample holder placed on the substrate.
  • the grid is made with one or more materials with high electronic emissivity.
  • refractory materials such as for example molybdenum or tungsten, to obtain a longer lifetime of the grid and limit the deformation due to the temperatures it can reach.
  • These refractory materials can optionally be doped, for example with thorium, to increase their electronic emissivity. Indeed the peak effect, created on the whole surface of the grid and by each of the elements which compose it, converts it into a structure of a large surface of emission of electrons.
  • the grid 20 shown here is of circular section, but any other section can be envisaged.
  • the shape can be chosen according to the shape of the diamond that one wants to obtain.
  • the grid mesh and / or its height can also be adapted according to the dimensions and / or characteristics of the chamber, the electrodes and / or the chamber.
  • the height of the grid can be the same around the entire periphery of its section or variable, for example in corners, to compensate for electronic effects which would lead to an inhomogeneous deposit of diamond.
  • the grid, the rings or the tube thus defined are plasma compression means which have the function of:
  • Diamond being an electrical insulator, as the layer of diamond deposited on the substrate thickens, it forms a barrier to the direct current passing between the electrodes 4 and 5, in particular when the layer of diamond reaches 25 to 30 ⁇ m thick. Consequently, for the same applied voltage, the density of the reactive carbon atoms in the plasma decreases as a function of the thickness of the diamond layer. The speed of diamond deposition decreases as the thickness of the already formed layer increases.
  • the applicant proposes to combine the source of direct current (DC) with a source of current by radio frequencies (RF) and therefore to create the plasma by application, between the two electrodes, direct current and alternating current at radio frequency (RF).
  • DC direct current
  • RF radio frequencies
  • the electrodes 4 and 5 are connected to a source 46 of alternating current at radio frequency and to a ground 47, in parallel with the circuit comprising the source 6 direct current.
  • the source 46 of alternating current at radio frequency preferably comprises, at its output, a filter preventing the direct current from the source 6 from entering back into the source 46.
  • the source 6 of direct current also preferably comprises, at its output a filter preventing the alternating current at radio frequency from the source 46 from entering back into the source 6.
  • a direct current and an alternating current at radio frequency are applied between the electrodes 4 and 5.
  • the ratio between the two currents can be constant during the synthesis. It has been observed, surprisingly, that the DC / RF ratio has an effect on the crystal form of the diamond depositing on the substrate. For example, in a configuration allowing the formation, on a substrate of ultra-nanocrystals of diamond with the application of a DC current only, the application of RF current in an RF / DC power ratio of 0.05 to 0.3 allows to obtain a deposit formed by larger crystals, that is to say of sub-micrometric dimension at several ten microns.
  • the ratio between the two currents can be variable during the synthesis, in order to optimize the synthesis speed.
  • the RF current can gradually take over from the direct current as the layer of diamond deposited thickens.
  • the DC / RF ratio could for example also be selected according to the properties desired for the deposition.
  • the hybrid power supply system for plasma generating electrodes thus improves the speed of diamond deposition, by compensating for the electrical insulating effect of the diamond already deposited. It also allows you to play on characteristics such as the structure and properties of the deposit.
  • the RF current source can also be connected to the gate 20, in parallel with the direct current source. These sources can be the same as those supplying the electrodes, or separate sources. Each of these sources can be optionally connected via a power regulator in order to modulate the DC / RF power ratio supplied to the grid. This facilitates the emission of electrons from the grid.
  • a magnetic field can be applied to the plasma, preferably near the substrate. This makes it possible to reduce, or even avoid, the presence of holes in the diamond layer / film formed.
  • a permanent magnet 50 generating a magnetic field 51 represented by the dotted lines is placed under the substrate electrode 5.
  • the magnet or electromagnet
  • Electrodes 4 and 5 shown here are only powered by direct current. It is obviously possible to combine direct current with RF current here too.
  • a single magnet is shown here under the substrate 5, but it could be placed near the anode 4. There could also be several magnets, in particular one near the substrate 5 and one near the anode 4.
  • the charged atoms of the plasma 28, moving between the electrodes under the effect of the electric field created between the anode 4 and the cathode 5, are in addition subjected to the magnetic field 51, in the vicinity of the substrate. 5.
  • Their trajectory is thus deviated under the action of the Lorentz force, the effect of the two fields adding up on each charged / reactive atom: the charged atoms will then tend to follow a helical trajectory, longer than in the presence of a single field, forming loops around the magnetic field lines.
  • the addition of the effects of the two fields will also accelerate the movement of the reactive atoms.
  • Reactive atoms traveling faster over a longer trajectory then have a higher probability of collision, which results in an increase in the concentration of activated carbons and ultimately an increase in the rate of formation and deposition of the diamond on the substrate.
  • a permanent magnet has been described here, but any form of magnet, permanent or not, making it possible to generate an appropriate magnetic field in the vicinity of the substrate can be used.
  • the distance between the anode and the substrate / cathode can be adjusted to optimize the deposition.
  • the three elements of the invention the plasma compression means, the hybridization of the current sources and the application of a magnetic field in the vicinity of the substrate, each have, separately, a positive effect on the speed. diamond formation and deposition, linking these three elements by a unique inventive concept. This effect is all the more pronounced as two of these means, or the three means are used in combination, as illustrated in the following example.
  • UVCs generated in situ in the plasma contribute to improving the efficiency of the reaction, by promoting the dissociation of the reagent bonds to form the plasma. It is also possible, for the same effect of places to apply UVC near the substrate, where the plasma is formed. UVC lamps can be arranged in the chemical vapor deposition chamber.
  • photons of frequency and / or particular energies chosen to correspond to an absorption frequency of the material to be synthesized and / or of a reagent, can be sent to the substrate to improve the rate of formation of matter.
  • a 260 mm diameter and 160 mm high CVD chamber contains a 3.2 mm diameter tungsten anode placed approximately 35 mm above a 15 mm by 15 mm silicon substrate forming the cathode.
  • the grid is made of molybdenum and has a diameter of 5 cm in diameter, a height of about 1 cm and a mesh of 1 mm.
  • a transverse magnetic field of 0.02 T is produced by an electromagnet.
  • the two sources are applied here at the same time over the entire duration of the deposition.
  • the carbon-bearing gas introduced into the chamber consists of a mixture of 3% methane in 97% hydrogen.
  • the pressure is brought to approximately 300 mBar and stabilized in order to ensure the stability of the plasma.
  • the temperature in the chamber during the synthesis is approximately 950 ° C., which here corresponds to the optimal temperature for deposition on a silicon substrate.
  • the direct current applied is a direct current of 735 V, with a power of approximately 1200 W ( ⁇ 100W).
  • the simple presence of the grid makes it possible to double the speed of deposition and to homogenize the nature of the film.
  • the combination of the grid and the hybrid DC / RF power source accelerates more than six times the deposition rate.
  • the magnetic field applied here makes it possible to avoid the discharges coming from specific electric arcs and leading to the presence of holes in the diamond deposit and also by itself alone allows to almost double the speed of deposit.
  • the nature of the substrate influences the crystal form of the diamond, depending on whether it is, for example made of silicon, molybdenum, tungsten, titanium or quartz.
  • the plasma compression means can be applied to any other type of synthesis by chemical vapor deposition, at atmospheric pressure or at low pressure, in order to to improve the speed of deposition. It is the same for DC / RF hybridization and / or the application of a magnetic field near the substrate.

Abstract

The invention relates to the improvement of the synthesis by chemical vapor deposition, particularly the diamond synthesis. According to the invention, it is proposed to reduce the time required for depositing diamond layers by compressing the plasma near the deposition substrate in order to increase the chances of collision between active species.

Description

Procédé et dispositif de synthèse de diamant par CVD  Method and device for diamond synthesis by CVD
L'invention concerne le domaine de la synthèse de diamant ou toute autre forme allotropique de carbone par dépôt chimique en phase vapeur.  The invention relates to the field of diamond synthesis or any other allotropic form of carbon by chemical vapor deposition.
Le carbone est un matériau présentant plusieurs formes allotropiques, naturellement à l'état solide sur terre, qui sont le carbone amorphe et trois formes cristallisées, le graphite, le diamant et la lonsdaléite. Le diamant est principalement constitué d'atomes de carbone hybridés sp3 alors que le graphite est principalement constitué de carbone hybridé sp2. D'autres formes allotropiques existent, à l’état synthétique, comme le DLC. Carbon is a material having several allotropic forms, naturally in the solid state on earth, which are amorphous carbon and three crystallized forms, graphite, diamond and lonsdaleite. The diamond consists mainly of sp 3 hybridized carbon atoms while the graphite consists mainly of sp 2 hybridized carbon. Other allotropic forms exist, in a synthetic state, such as DLC.
Le diamant est un matériau possédant une combinaison unique de propriétés, comme la résistance à l'usure, la conductivité thermique ou l'isolation électrique, très intéressantes pour de nombreuses applications techniques. La rareté et le prix du diamant naturel rendent son utilisation à grande échelle impossible et le cantonnent à la bijouterie de luxe. Cependant, au cours des dernières décennies, des méthodes de synthèse de diamant ont été développées, dans l'espoir de faciliter l'accès à ce matériau à plus grande échelle pour des applications techniques.  Diamond is a material with a unique combination of properties, such as resistance to wear, thermal conductivity or electrical insulation, which are very interesting for many technical applications. The rarity and the price of natural diamonds make its use on a large scale impossible and confine it to luxury jewelry. However, in recent decades, methods of diamond synthesis have been developed, in the hope of facilitating access to this material on a larger scale for technical applications.
Le DLC ou « Diamond Like Carbon » est également un matériau intéressant, se différenciant du diamant par une proportion de carbone d'hybridation sp2, jusqu'à 60%, dans du carbone d'hybridation sp3. DLC or “Diamond Like Carbon” is also an interesting material, differentiating from diamond by a proportion of sp 2 hybridization carbon, up to 60%, in sp 3 hybridization carbon.
La méthode de choix pour la synthèse de couches minces de diamant ou DLC sur un substrat est le dépôt chimique en phase vapeur ou CVD (Chemical vapor déposition) à basse pression. Selon cette méthode du diamant est déposé sous forme cristalline sur un substrat placé dans une chambre dans laquelle on introduit un gaz porteur d'atomes de carbone qui est transformé en plasma par une source d'énergie.  The method of choice for the synthesis of thin diamond layers or DLC on a substrate is chemical vapor deposition or CVD (Chemical vapor deposition) at low pressure. According to this method, the diamond is deposited in crystalline form on a substrate placed in a chamber into which a gas carrying carbon atoms is introduced which is transformed into plasma by an energy source.
Plusieurs technologies peuvent être utilisées pour la formation du plasma, comme par exemple un courant continu, un arc électrique, un filament chaud ou des microondes, entre autres. Actuellement, les appareils) qui dominent le marché utilisent les microondes ou un filament chaud.  Several technologies can be used for the formation of plasma, such as for example a direct current, an electric arc, a hot filament or microwaves, among others. Currently, the devices that dominate the market use microwaves or a hot filament.
Le principal inconvénient de ces méthodes est la très faible vitesse de déposition de diamant. La technologie à filament chaud permet de former des couches de diamant d'environ 1 pm par heure. Ces couches sont en plus fréquemment contaminées par des éléments du filament. Les microondes permettent d'améliorer la vitesse de déposition à environ 45 pm par heure, mais limitent techniquement le diamètre de déposition à environ 16 mm, du fait de la longueur d'ondes. Il faut donc des temps de réaction considérables pour former des couches très fines de diamant, ce qui rend ces méthodes industriellement non développables en termes de coût énergétique, d'efficacité du temps d'occupation des équipements et donc de coût de production. Ces limitations des méthodes existantes sont développées en détail par A. Tallaire dans C. R. Physique 14 (2013) 169-184. Les diamants produits synthétiquement en couches minces restent donc pour l'instant limités à des applications dans le domaine du forage pétrolier ou minier. The main disadvantage of these methods is the very low rate of diamond deposition. Hot filament technology makes it possible to form diamond layers of around 1 µm per hour. These layers are more frequently contaminated by elements of the filament. Microwaves make it possible to improve the deposition speed to approximately 45 μm per hour, but technically limit the deposition diameter to approximately 16 mm, due to the wavelength. It therefore takes considerable reaction times to form very thin layers of diamond, which makes these methods industrially non-developable in terms of energy cost, efficiency of the equipment occupation time and therefore production cost. These limitations of existing methods are developed in detail by A. Tallaire in CR Physique 14 (2013) 169-184. Diamonds produced synthetically in thin layers therefore remain for the moment limited to applications in the field of oil or mining drilling.
Dans un souci de rendre techniquement et économiquement accessible le matériau diamant à de nombreuses application techniques, il a été jugé nécessaire par la demanderesse de proposer une méthode de synthèse de diamant permettant d'améliorer la vitesse de déposition. C'est le problème qui est à l'origine de l'invention de la présente demande.  In order to make the diamond material technically and economically accessible to many technical applications, it was deemed necessary by the applicant to propose a method of diamond synthesis making it possible to improve the speed of deposition. This is the problem which is at the origin of the invention of the present application.
A cette fin, l'invention concerne tout d'abord un procédé de synthèse de diamant, dans une chambre de déposition en phase vapeur et sur un substrat de synthèse, entre deux électrodes de génération de plasma, selon lequel : To this end, the invention relates first of all to a method of diamond synthesis, in a vapor deposition chamber and on a synthesis substrate, between two plasma generation electrodes, according to which:
on introduit dans la chambre un gaz porteur d'atomes de carbone et on créé un plasma à proximité du substrat pour générer des atomes de carbone réactifs,  a gas carrying carbon atoms is introduced into the chamber and a plasma is created near the substrate to generate reactive carbon atoms,
procédé caractérisé par le fait qu'on comprime le plasma pour augmenter, à proximité du substrat, la densité volumique des atomes de carbone réactifs et donc la vitesse de déposition. process characterized by the fact that the plasma is compressed to increase, near the substrate, the density of the reactive carbon atoms and therefore the deposition rate.
L'invention concerne aussi un procédé de synthèse de diamant, dans une chambre (1) de déposition en phase vapeur et sur un substrat (5) de synthèse, entre deux électrodes (4, 5) de génération de plasma, selon lequel :  The invention also relates to a method of diamond synthesis, in a vapor deposition chamber (1) and on a synthesis substrate (5), between two electrodes (4, 5) for generating plasma, according to which:
on introduit dans la chambre (1) un gaz porteur d'atomes de carbone et on créé un plasma (28) à proximité du substrat pour générer des atomes de carbone réactifs, procédé caractérisé par le fait qu'on crée le plasma par application, entre les deux électrodes, d'un courant continu (DC) (6) et d'un courant alternatif à fréquence radio (RF) (46). a gas carrying carbon atoms is introduced into the chamber (1) and a plasma (28) is created near the substrate to generate reactive carbon atoms, process characterized by the fact that the plasma is created by applying, between the two electrodes, a direct current (DC) (6) and an alternating current at radio frequency (RF) (46).
L'invention concerne également et enfin un procédé de synthèse de diamant, dans une chambre (1) de déposition en phase vapeur et sur un substrat (5) de synthèse, entre deux électrodes (4, 5) de génération de plasma, selon lequel :  The invention also relates, finally, to a method of diamond synthesis, in a vapor deposition chamber (1) and on a synthesis substrate (5), between two electrodes (4, 5) for generating plasma, according to which :
on introduit dans la chambre (1) un gaz porteur d'atomes de carbone et on créé un plasma (28) à proximité du substrat pour générer des atomes de carbone réactifs,  a gas carrying carbon atoms is introduced into the chamber (1) and a plasma (28) is created near the substrate to generate reactive carbon atoms,
procédé caractérisé par le fait qu'on applique, à proximité du substrat, un champ magnétique (51). process characterized by the fact that a magnetic field (51) is applied near the substrate.
Par diamant, on désigne ici, et dans la suite de la description, toutes les formes allotropiques contenant du carbone à l'état d'hybridation sp3, comme notamment le diamant, dans toutes ses formes cristallines ou le DLC. By diamond, here is meant, and in the following description, all allotropic forms containing carbon in the sp 3 hybridization state, such as in particular diamond, in all its crystalline forms or DLC.
En référence à la première mise en œuvre de l'invention, les atomes de carbone réactifs sont typiquement des atomes de carbone sous forme « activée », c'est-à-dire radicalaire ou ionique. Cette expression désigne ici également des molécules carbonées dans une forme activée, c'est à dire radicalaire ou ionique.  With reference to the first implementation of the invention, the reactive carbon atoms are typically carbon atoms in "activated" form, that is to say radical or ionic. This expression also designates here carbonaceous molecules in an activated form, that is to say radical or ionic.
Comprimer le plasma consiste à guider, ou focaliser, les espèces réactives du plasma, comme les radicaux et les ions produits entre les électrodes, dans une région restreinte entre les deux électrodes afin d'en augmenter la concentration et, en conséquence, la probabilité des chocs réactionnels entre radicaux. L'augmentation du nombre de chocs permet également de générer des photons UVC, voire infra-rouge, qui permettent eux-mêmes de générer des atomes réactifs supplémentaires. La combinaison de ces effets permet d'améliorer considérablement la vitesse de déposition de diamant sur le substrat.  Compressing the plasma consists of guiding, or focusing, the reactive plasma species, such as the radicals and the ions produced between the electrodes, in a restricted region between the two electrodes in order to increase their concentration and, consequently, the probability of reaction shocks between radicals. The increase in the number of shocks also makes it possible to generate UVC, or even infrared, photons which themselves make it possible to generate additional reactive atoms. The combination of these effects makes it possible to considerably improve the speed of deposition of diamond on the substrate.
En référence à la deuxième mise en œuvre de l'invention, en général, les électrodes entre lesquelles est généré le plasma sont alimentées par une source de courant continu (DC). Cette source d'énergie est efficace pour commencer le dépôt de diamant. Néanmoins, lorsque l'épaisseur de la couche formée devient conséquente, à partir par exemple de 25-30 pm, à la température régnant dans la chambre, par exemple entre 300 et 1600 °C, la couche de diamant devient un isolant électrique suffisant pour réduire sensiblement le passage de l'énergie entre les électrodes et par conséquent diminuer la vitesse de synthèse du diamant. With reference to the second implementation of the invention, in general, the electrodes between which the plasma is generated are supplied by a source of direct current (DC). This energy source is effective in starting the diamond deposit. However, when the thickness of the layer formed becomes substantial, for example from 25-30 μm, at the temperature prevailing in the chamber, for example example between 300 and 1600 ° C, the diamond layer becomes an electrical insulator sufficient to significantly reduce the passage of energy between the electrodes and therefore decrease the diamond synthesis speed.
Pour pallier cet effet, la demanderesse propose une hybridation de la génération d'énergie et de combiner la source de courant continu (DC) à une source de courant par radiofréquences (RF) et donc de créer le plasma par application, entre les deux électrodes, d'un courant continu et d'un courant alternatif à fréquence radio (RF). La source de courant continu (DC) peut être permanente ou hachée.  To overcome this effect, the applicant proposes a hybridization of the generation of energy and to combine the source of direct current (DC) with a current source by radiofrequencies (RF) and thus to create the plasma by application, between the two electrodes , direct current and alternating current at radio frequency (RF). The direct current (DC) source can be permanent or chopped.
Le ratio DC/RF peut être modulable au cours de la synthèse, en particulier en fonction de l'épaisseur de diamant déjà synthétisée, pour que la vitesse de dépôt de diamant reste constante.  The DC / RF ratio can be adjustable during the synthesis, in particular as a function of the thickness of diamond already synthesized, so that the speed of diamond deposition remains constant.
Il a également été trouvé, de façon surprenante, que le ratio DC/RF a un impact sur la structure cristalline du diamant formé : monocristaux, poly-cristaux de taille variable et ajustable.  It has also been surprisingly found that the DC / RF ratio has an impact on the crystal structure of the diamond formed: single crystals, poly-crystals of variable and adjustable size.
En référence à la troisième mise en œuvre de l'invention, pour homogénéiser la répartition des atomes de carbone réactifs dans le plasma, on peut appliquer, à proximité du substrat, un champ magnétique. Les atomes réactifs, au lieu de suivre une trajectoire directe entre les électrodes, acquièrent en plus un mouvement de boucle, ou de tendance hélicoïdale. Les atomes réactifs parcourent ainsi un chemin plus long et prennent plus de vitesse, augmentant la probabilité des collisions, génératrices des liaisons C-C d'hybridation sp3 caractéristiques du diamant, et par conséquent la vitesse de synthèse. Cela permet également d'éviter les arcs et les trous dans la couche ou le film de diamant formé.  With reference to the third implementation of the invention, to homogenize the distribution of the reactive carbon atoms in the plasma, it is possible to apply, near the substrate, a magnetic field. The reactive atoms, instead of following a direct trajectory between the electrodes, acquire in addition a movement of loop, or of helical tendency. The reactive atoms thus travel a longer path and gain more speed, increasing the probability of collisions, generating the C-C sp3 hybridization bonds characteristic of diamonds, and therefore the speed of synthesis. This also helps to avoid arcs and holes in the diamond layer or film formed.
L'application d'un champ magnétique permet à lui seul d'augmenter la vitesse de dépôt du diamant. Il peut néanmoins avantageusement être combiné avec la compression du plasma et/ou l'hybridation des sources d'énergie DC/RF.  The application of a magnetic field alone increases the speed of deposition of the diamond. However, it can advantageously be combined with plasma compression and / or hybridization of DC / RF energy sources.
On a donc démontré que les trois mises en œuvre du procédé de l'invention visent à résoudre le même et unique problème d'augmentation de la vitesse de synthèse dans un but économique. En d'autres termes, l'invention de la présente demande est une invention de problème résolu de trois manières différentes et qui peuvent d'ailleurs se combiner. Les exigences d'unicité d'invention de la demande de brevet sont donc parfaitement remplies. It has therefore been demonstrated that the three implementations of the process of the invention aim to solve the same and only problem of increasing the speed of synthesis for an economic purpose. In other words, the invention of the present application is an invention of a problem solved in three different ways and which can moreover be combined. The uniqueness of invention requirements of the patent application are therefore perfectly fulfilled.
En réalité, la demanderesse n'entend pas limiter la portée de sa demande à la synthèse de diamant. Le procédé de l'invention peut bénéficier à toute autre matière synthétisable par dépôt chimique en phase vapeur, comme, par exemple, des semi- conducteurs de type Si-Ge à partir d'un gaz porteur de silicium et un gaz porteur de germanium, ou des oxydes ou nitrures de silicium. Ainsi, la présente invention concerne d'abord les procédés des revendications 1-3.  In reality, the plaintiff does not intend to limit the scope of its request to diamond synthesis. The process of the invention can benefit any other material which can be synthesized by chemical vapor deposition, such as, for example, Si-Ge type semiconductors from a silicon-bearing gas and a germanium-bearing gas, or silicon oxides or nitrides. Thus, the present invention first relates to the methods of claims 1-3.
Par diamant, l'invention ne se limite pas ici au diamant pur, mais peut également s'appliquer au dopage du diamant. Par exemple, le diamant peut être dopé par du bore ; on introduit alors dans la chambre, en plus du gaz porteur d'atomes de carbone, un gaz porteur de bore comme le triméthylborane, le trichlorure de bore ou le diborane. Le diamant peut également être dopé par de l'azote ; on introduit alors dans la chambre, en plus du gaz porteur d'atomes de carbone, un gaz porteur d'azote comme di diazote, de l'ammoniac ou de la méthyl amine.  By diamond, the invention is not limited here to pure diamond, but can also be applied to doping diamond. For example, the diamond can be doped with boron; then introduced into the chamber, in addition to the gas carrying carbon atoms, a boron-carrying gas such as trimethylborane, boron trichloride or diborane. Diamond can also be doped with nitrogen; is then introduced into the chamber, in addition to the gas carrying carbon atoms, a nitrogen-bearing gas such as dinitrogen, ammonia or methyl amine.
Pour la mise en œuvre du procédé, l'invention concerne également une chambre de déposition en phase vapeur, pourvue d'une entrée de gaz et d'une sortie de gaz, et à l'intérieur de laquelle sont agencées deux électrodes de génération de plasma reliées à une source de courant continu (DC), caractérisé par le fait que des moyens de compression de plasma sont fournis entre les deux électrodes. For implementing the method, the invention also relates to a vapor deposition chamber, provided with a gas inlet and a gas outlet, and inside which are arranged two electrodes for generating plasma connected to a direct current (DC) source, characterized in that plasma compression means are provided between the two electrodes.
Selon un mode de réalisation particulier, les deux électrodes sont en outre reliées à une source de courant alternatif à fréquence radio (RF). According to a particular embodiment, the two electrodes are also connected to a source of alternating current at radio frequency (RF).
De préférence, les deux électrodes sont une anode et une cathode, la cathode formant un substrat de déposition de diamant.  Preferably, the two electrodes are an anode and a cathode, the cathode forming a diamond deposition substrate.
Il est également possible de fournir, dans la chambre, des moyens de génération d'un champ magnétique à proximité du substrat.  It is also possible to provide, in the chamber, means for generating a magnetic field near the substrate.
L'invention sera mieux comprise à l'aide de la description suivante de la forme de réalisation préférée de l'invention, en référence au dessin en annexe sur lequel : La figure 1 illustre schématiquement une chambre de déposition en phase vapeur de l'art antérieur ; The invention will be better understood with the aid of the following description of the preferred embodiment of the invention, with reference to the attached drawing in which: Figure 1 schematically illustrates a vapor deposition chamber of the prior art;
La figure 2 illustre schématiquement une chambre de déposition en phase vapeur selon l'invention;  Figure 2 schematically illustrates a vapor deposition chamber according to the invention;
La figure 3 est une vue en perspective des électrodes et de la grille de la figure 2.  FIG. 3 is a perspective view of the electrodes and of the grid of FIG. 2.
En référence à la figure 1, une chambre 1 de déposition en phase vapeur (CVD) comprend une arrivée 2 de gaz, une sortie 3 de dépressurisation, des électrodes, une anode 4 et un substrat 5 formant cathode, connectées aux bornes d'une alimentation 6 de courant continu, le circuit étant relié à la masse 7. With reference to FIG. 1, a vapor deposition chamber 1 (CVD) comprises an inlet 2 for gas, an outlet 3 for depressurization, electrodes, an anode 4 and a substrate 5 forming a cathode, connected to the terminals of a DC power supply 6, the circuit being connected to earth 7.
Pour procéder à la synthèse de diamant, un gaz porteur d'atomes de carbone, par exemple du méthane ou de l'éthane, est introduit par l'entrée 2, la pression dans la chambre 1 est réduite par application d'un vide à la sortie 3 et une tension est appliquée entre les électrodes 4 et 5. Sous l'effet de la tension entre les électrodes, les molécules du gaz porteur d'atomes de carbone sont activées pour former un plasma dans un large volume 8. Le volume 8 de plasma déborde de la zone strictement comprise entre les électrodes.  To carry out diamond synthesis, a gas carrying carbon atoms, for example methane or ethane, is introduced via inlet 2, the pressure in chamber 1 is reduced by applying a vacuum to the output 3 and a voltage is applied between the electrodes 4 and 5. Under the effect of the voltage between the electrodes, the molecules of the gas carrying carbon atoms are activated to form a plasma in a large volume 8. The volume 8 of plasma extends beyond the area strictly between the electrodes.
L'énergie appliquée entre les électrodes a notamment pour effet de dissocier certaines liaisons, comme par exemple les liaisons C-H, générant ainsi des espèces réactives, comme par exemple des radicaux de carbone et d'hydrogène. Ces radicaux peuvent ensuite soit se réassocier à des radicaux d'hydrogène, soit à d'autres radicaux de carbone, conduisant ainsi à la formation d'une liaison C-C, les radicaux hydrogène peuvent également s'associer entre eux pour former de hydrogène gazeux qui peux être évacué de la chambre par la sortie 3.  The energy applied between the electrodes has the particular effect of dissociating certain bonds, such as for example C-H bonds, thus generating reactive species, such as for example carbon and hydrogen radicals. These radicals can then either reassociate themselves with hydrogen radicals, or with other carbon radicals, thus leading to the formation of a CC bond, the hydrogen radicals can also associate with each other to form hydrogen gas which can be evacuated from the room by exit 3.
L'énergie de la liaison C-C étant plus faible que celle de la liaison C-H, l'équilibre réactionnel est ainsi déplacé vers le remplacement progressif de toutes les liaisons C-H par des liaisons C-C, c'est-à-dire la formation de diamant. Plus le réseau de liaison C-C devient important, moins l'espèce est volatile et les molécules formées se déposent par gravité sur le substrat. Le substrat peut en outre contenir des espèces qui permettent d'initier à son contact la formation de liaisons C-C. Les radicaux libres sont une espèce instable présentant une durée de vie très longue en milieu gazeux. Même si les la formation d'un lien moléculaire à partir de la liaison pendante du radical est très favorable énergétiquement elle nécessite un choc à trois corps afin de permettre la conservation de la quantité de mouvement. C'est donc un phénomène très rare. Il en est tout autrement en surface, un radical gazeux s'associe facilement avec un centre radicalaire de la surface, car les phonons peuvent alors assurer la conservation de la quantité de mouvement. The energy of the CC bond being weaker than that of the CH bond, the reaction equilibrium is thus shifted towards the gradual replacement of all the CH bonds by CC bonds, that is to say the diamond formation. The larger the CC link network becomes, the less volatile the species and the molecules formed are deposited by gravity on the substrate. The substrate may also contain species which make it possible to initiate, on contact, the formation of CC bonds. Free radicals are an unstable species with a very long life in a gaseous medium. same if the formation of a molecular bond starting from the pendant bond of the radical is very energetically favorable it requires a shock to three bodies in order to allow the conservation of the momentum. It is therefore a very rare phenomenon. It is quite different on the surface, a gas radical associates easily with a radical center of the surface, because the phonons can then ensure the conservation of the momentum.
Optionnellement, un porte échantillon peut être placé sur le substrat afin de conférer des dimensions spécifiques au dépôt, ou pour éviter le dépôt directement sur l'électrode.  Optionally, a sample holder can be placed on the substrate in order to give specific dimensions to the deposit, or to avoid deposit directly on the electrode.
La probabilité de collisions entre atomes de carbone réactifs est directement proportionnelle à la densité volumique des atomes de ces atomes de carbone réactifs dans la zone 8, qui est elle-même liée à l'énergie appliquée entre les deux électrodes 4 et 5.  The probability of collisions between reactive carbon atoms is directly proportional to the density of the atoms of these reactive carbon atoms in zone 8, which is itself linked to the energy applied between the two electrodes 4 and 5.
En référence aux figures 2 et 3, où la numérotation de la figure 1 est réutilisée pour les éléments identiques, les électrodes 4 et 5 sont ici des disques parallèles dont les centres sont placés le long d'un axe AA'. Une grille 20, épousant ici le pourtour d'un cylindre d'axe AA', est placée dans la chambre entre les électrodes 4 et 5. La grille 20 est reliée à une source de courant continu.  With reference to FIGS. 2 and 3, where the numbering in FIG. 1 is reused for the identical elements, the electrodes 4 and 5 are here parallel disks whose centers are placed along an axis AA '. A grid 20, matching here the periphery of a cylinder with axis AA ', is placed in the chamber between the electrodes 4 and 5. The grid 20 is connected to a source of direct current.
L'électrode 4 pourrait avoir d'autres formes, comme par exemple être constituée d'une seule ou d'un ensemble de pointes à extrémité sphérique dirigée(s) selon l'axe AA'. L'électrode 4 peut avoir une forme concave, convexe ou plate  The electrode 4 could have other forms, such as for example being made up of a single or of a set of points with a spherical end directed along the axis AA ′. The electrode 4 can have a concave, convex or flat shape
Pour réaliser la synthèse du diamant, la chambre 1 est mise sous faible pression (pression inférieure à la pression atmosphérique) de gaz porteur d'atomes de carbones, en ouvrant l'entrée 2 de gaz et en appliquant une dépression à la sortie 3. Un courant continu est appliqué entre les électrodes 4 et 5, générant un plasma d'atomes de carbones réactifs entre les électrodes. Simultanément, un courant continu est appliqué à la grille 20 afin de créer aux abords du cylindre qu'elle définit, un champ électrique ayant pour effet d'orienter les atomes de carbone réactifs du plasma dans une zone 28 définie entre les électrodes 4 et 5 et limitée en largeur par l'intérieur du cylindre formé par la grille 20. Du diamant se dépose progressivement sur le substrat 5, en une couche homogène. Pour une même énergie appliquée entre les électrodes 4 et 5 entre les dispositifs des figures 1 et 2, c'est-à-dire a priori la même quantité d'atomes de carbone réactifs, la zone d'extension du plasma est réduite en présence de la grille 20, le plasma est comprimé, augmentant ainsi la densité volumique des atomes de carbone réactifs. La probabilité des collisions entre atomes de carbone réactifs et avec la surface est ainsi augmentée ce qui permet d'augmenter la vitesse de formation et de déposition de diamant sur le substrat, ou optionnellement sur un porte-échantillon placé sur le substrat. To carry out the synthesis of the diamond, the chamber 1 is placed under low pressure (pressure below atmospheric pressure) of gas carrying carbon atoms, by opening the gas inlet 2 and applying a vacuum at the outlet 3. Direct current is applied between electrodes 4 and 5, generating a plasma of reactive carbon atoms between the electrodes. Simultaneously, a direct current is applied to the grid 20 in order to create around the cylinder which it defines, an electric field having the effect of orienting the reactive carbon atoms of the plasma in a zone 28 defined between the electrodes 4 and 5 and limited in width by the interior of the cylinder formed by the grid 20. Diamond is gradually deposited on the substrate 5, in a homogeneous layer. For the same energy applied between the electrodes 4 and 5 between the devices of FIGS. 1 and 2, that is to say a priori the same quantity of reactive carbon atoms, the plasma extension zone is reduced in the presence grid 20, the plasma is compressed, thereby increasing the density of the reactive carbon atoms. The probability of collisions between reactive carbon atoms and with the surface is thus increased, which makes it possible to increase the speed of formation and deposition of diamond on the substrate, or optionally on a sample holder placed on the substrate.
De préférence, la grille est fabriquée avec un ou plusieurs matériaux à forte émissivité électronique. Il est intéressant d'utiliser des matériaux réfractaires, comme par exemple le molybdène ou le tungstène, pour obtenir une plus longue durée de vie de la grille et en limiter la déformation due aux températures qu'elle peut atteindre. Ces matériaux réfractaires peuvent éventuellement être dopé, par exemple par du thorium, pour en augmenter l'émissivité électronique. En effet l'effet de pointe, créé sur toute la surface de la grille et par chacun des éléments qui la composent, la convertit en une structure d'une grande surface d'émission d'électrons.  Preferably, the grid is made with one or more materials with high electronic emissivity. It is advantageous to use refractory materials, such as for example molybdenum or tungsten, to obtain a longer lifetime of the grid and limit the deformation due to the temperatures it can reach. These refractory materials can optionally be doped, for example with thorium, to increase their electronic emissivity. Indeed the peak effect, created on the whole surface of the grid and by each of the elements which compose it, converts it into a structure of a large surface of emission of electrons.
La grille 20 ici représentée est de section circulaire, mais toute autre section peut être envisagée. En particulier, la forme peut être choisie en fonction de la forme du diamant que l'on veut obtenir. Le maillage de la grille et/ou sa hauteur peuvent également être adaptés en fonction des dimensions et/ou des caractéristiques de la chambre, des électrodes et/ou de la chambre. La hauteur de la grille peut être la même sur tout le pourtour de sa section ou variable, par exemple dans des coins, pour compenser des effets électroniques qui conduiraient à un dépôt non homogène de diamant.  The grid 20 shown here is of circular section, but any other section can be envisaged. In particular, the shape can be chosen according to the shape of the diamond that one wants to obtain. The grid mesh and / or its height can also be adapted according to the dimensions and / or characteristics of the chamber, the electrodes and / or the chamber. The height of the grid can be the same around the entire periphery of its section or variable, for example in corners, to compensate for electronic effects which would lead to an inhomogeneous deposit of diamond.
De même, à la place d'une grille, il est possible d'utiliser un ou plusieurs anneaux, qui peuvent être de même diamètre ou de diamètres différents, et dont les centres seraient alignés sur l'axe AA'. Il est également possible d'utiliser un tube.  Similarly, instead of a grid, it is possible to use one or more rings, which may be of the same diameter or of different diameters, and whose centers would be aligned on the axis AA ′. It is also possible to use a tube.
La grille, les anneaux ou le tube ainsi définis sont des moyens de compression du plasma qui ont pour fonction :  The grid, the rings or the tube thus defined are plasma compression means which have the function of:
d'homogénéiser le plasma autour du substrat ou de la zone particulière ou le diamant doit être déposé, d'augmenter la densité volumique des atomes de carbone réactifs dans cette zone, to homogenize the plasma around the substrate or the particular area where the diamond must be deposited, to increase the density of reactive carbon atoms in this area,
de générer des photons UVC voire IR, et éventuellement d'émettre des électrons pour fournir de l'énergie supplémentaire et ajouter à la densification du plasma.  generate UVC or even IR photons, and possibly emit electrons to provide additional energy and add to the densification of the plasma.
Le diamant étant un isolant électrique, au fur et à mesure que la couche de diamant déposée sur le substrat s'épaissit, elle forme une barrière au courant continu passant entre les électrodes 4 et 5, en particulier lorsque la couche de diamant atteint 25 à 30 pm d'épaisseur. En conséquence, pour une même tension appliquée, la densité volumique des atomes de carbone réactifs dans le plasma diminue en fonction de l'épaisseur de la couche de diamant. La vitesse de déposition de diamant diminue lorsque l'épaisseur de la couche déjà formée augmente.  Diamond being an electrical insulator, as the layer of diamond deposited on the substrate thickens, it forms a barrier to the direct current passing between the electrodes 4 and 5, in particular when the layer of diamond reaches 25 to 30 µm thick. Consequently, for the same applied voltage, the density of the reactive carbon atoms in the plasma decreases as a function of the thickness of the diamond layer. The speed of diamond deposition decreases as the thickness of the already formed layer increases.
Pour pouvoir former des couches plus épaisses que quelques dizaines de microns, la demanderesse propose de combiner la source de courant continu (DC) à une source de courant par radiofréquences (RF) et donc de créer le plasma par application, entre les deux électrodes, d'un courant continu et d'un courant alternatif à fréquence radio (RF).  To be able to form layers thicker than a few tens of microns, the applicant proposes to combine the source of direct current (DC) with a source of current by radio frequencies (RF) and therefore to create the plasma by application, between the two electrodes, direct current and alternating current at radio frequency (RF).
En référence à la figure 4, reprenant pour les éléments communs, la numérotation des figures précédentes, les électrodes 4 et 5 sont connectées à une source 46 de courant alternatif à fréquence radio et à une masse 47, en parallèle du circuit comprenant la source 6 de courant continu.  With reference to FIG. 4, repeating for the common elements, the numbering of the preceding figures, the electrodes 4 and 5 are connected to a source 46 of alternating current at radio frequency and to a ground 47, in parallel with the circuit comprising the source 6 direct current.
La source 46 de courant alternatif à fréquence radio comporte, de préférence, à sa sortie un filtre empêchant le courant continu de la source 6 de pénétrer en retour dans la source 46. La source 6 de courant continu comporte également, de préférence, à sa sortie un filtre empêchant le courant alternatif à fréquence radio de la source 46 de pénétrer en retour dans la source 6.  The source 46 of alternating current at radio frequency preferably comprises, at its output, a filter preventing the direct current from the source 6 from entering back into the source 46. The source 6 of direct current also preferably comprises, at its output a filter preventing the alternating current at radio frequency from the source 46 from entering back into the source 6.
Au cours de la synthèse, dans cette configuration, on applique, entre les électrodes 4 et 5 un courant continu et un courant alternatif à fréquence radio.  During the synthesis, in this configuration, a direct current and an alternating current at radio frequency are applied between the electrodes 4 and 5.
Le ratio entre les deux courants, ratio DC/RF, peut être constant au cours de la synthèse. Il a été observé, de façon surprenante, que le ratio DC/RF a une incidence sur la forme cristalline du diamant se déposant sur le substrat. Par exemple, dans une configuration permettant de former, sur un substrat des ultra-nano-cristaux de diamant avec l'application d'un courant DC uniquement, l'application de courant RF dans un rapport de puissance RF / DC de 0.05 à 0.3permet d'obtenir un dépôt formé par des cristaux plus grand, c'est-à-dire de dimension sub-micrométrique à plusieurs dizaine de microns. The ratio between the two currents, DC / RF ratio, can be constant during the synthesis. It has been observed, surprisingly, that the DC / RF ratio has an effect on the crystal form of the diamond depositing on the substrate. For example, in a configuration allowing the formation, on a substrate of ultra-nanocrystals of diamond with the application of a DC current only, the application of RF current in an RF / DC power ratio of 0.05 to 0.3 allows to obtain a deposit formed by larger crystals, that is to say of sub-micrometric dimension at several ten microns.
Le ratio entre les deux courants, ratio DC/RF, peut être variable au cours de la synthèse, afin d'optimiser la vitesse de synthèse. Par exemple le courant RF peut progressivement prendre le relais du courant continu au fur et à mesure que la couche de diamant déposée s'épaissit. Le ratio DC/RF pourrait par exemple également être sélectionné en fonction des propriétés souhaitées pour le dépôt.  The ratio between the two currents, DC / RF ratio, can be variable during the synthesis, in order to optimize the synthesis speed. For example, the RF current can gradually take over from the direct current as the layer of diamond deposited thickens. The DC / RF ratio could for example also be selected according to the properties desired for the deposition.
Le système d'alimentation hybride des électrodes génératrices de plasma a ainsi pour effet d'améliorer la vitesse de déposition de diamant, en compensant l'effet isolant électrique du diamant déjà déposé. Il permet également de jouer sur les caractéristiques telles que la structure et les propriétés du dépôt.  The hybrid power supply system for plasma generating electrodes thus improves the speed of diamond deposition, by compensating for the electrical insulating effect of the diamond already deposited. It also allows you to play on characteristics such as the structure and properties of the deposit.
La source de courant RF peut également être connectée à la grille 20, en parallèle de la source de courant continu. Ces sources peuvent être les mêmes que celles alimentant les électrodes, ou des sources distinctes. Chacune de ces sources peuvent être connectées optionnellement via un régulateur de puissance afin de moduler le ratio puissance DC/RF fournie à la grille. Cela permet de faciliter l'émission d'électrons à partir de la grille.  The RF current source can also be connected to the gate 20, in parallel with the direct current source. These sources can be the same as those supplying the electrodes, or separate sources. Each of these sources can be optionally connected via a power regulator in order to modulate the DC / RF power ratio supplied to the grid. This facilitates the emission of electrons from the grid.
Afin d'homogénéiser la répartition des charge positives et négatives dans le plasma, on peut appliquer, au niveau du plasma, de préférence à proximité du substrat, un champ magnétique. Cela permet de réduire, voire d'éviter, la présence de trous dans la couche/le film de diamant formé.  In order to homogenize the distribution of positive and negative charges in the plasma, a magnetic field can be applied to the plasma, preferably near the substrate. This makes it possible to reduce, or even avoid, the presence of holes in the diamond layer / film formed.
Alternativement ou en plus, il est également possible de placer un aimant à proximité de l'anode 4.  Alternatively or in addition, it is also possible to place a magnet near the anode 4.
En référence à la figure 5, reprenant pour les éléments communs, la numérotation des figures précédentes, un aimant permanent 50 générant un champ magnétique 51 représenté par les lignes pointillées est placé sous l'électrode substrat 5. L'aimant (ou électroaimant) est choisi ou placé pour pouvoir maximiser la composante radiale ou longitudinale ou les deux composantes du champ magnétique. Les électrodes 4 et 5 illustrées ici ne sont alimentées que par un courant continu. Il est évidemment possible de combiner ici aussi le courant continu avec un courant RF. With reference to FIG. 5, repeating for the common elements, the numbering of the preceding figures, a permanent magnet 50 generating a magnetic field 51 represented by the dotted lines is placed under the substrate electrode 5. The magnet (or electromagnet) is chosen or placed to be able to maximize the radial or longitudinal component or the two components of the magnetic field. Electrodes 4 and 5 shown here are only powered by direct current. It is obviously possible to combine direct current with RF current here too.
Un seul aimant est ici représenté sous le substrat 5, mais il pourrait être placé à proximité de l'anode 4. Il pourrait également y avoir plusieurs aimants, notamment un à proximité du substrat 5 et un à proximité de l'anode 4.  A single magnet is shown here under the substrate 5, but it could be placed near the anode 4. There could also be several magnets, in particular one near the substrate 5 and one near the anode 4.
Au cours de la synthèse, les atomes chargés du plasma 28, se mouvant entre les électrodes sous l'effet du champ électrique créé entre l'anode 4 et la cathode 5, sont en plus soumis au champ magnétique 51, dans le voisinage du substrat 5. Leur trajectoire est ainsi déviée sous l'action de la force de Lorentz, l'effet des deux champs s'additionnant sur chaque atome chargé/réactif : les atomes chargés vont alors avoir tendance à suivre une trajectoire hélicoïdale, plus longue qu'en présence d'un seul champ, formant des boucles autour des lignes de champ magnétique. L'addition des effets des deux champs va également accélérer le mouvement des atomes réactifs. During the synthesis, the charged atoms of the plasma 28, moving between the electrodes under the effect of the electric field created between the anode 4 and the cathode 5, are in addition subjected to the magnetic field 51, in the vicinity of the substrate. 5. Their trajectory is thus deviated under the action of the Lorentz force, the effect of the two fields adding up on each charged / reactive atom: the charged atoms will then tend to follow a helical trajectory, longer than in the presence of a single field, forming loops around the magnetic field lines. The addition of the effects of the two fields will also accelerate the movement of the reactive atoms.
Les atomes réactifs parcourant plus rapidement une trajectoire plus longue ont alors une probabilité de collision plus élevée, ce qui se traduit par une augmentation de la concentration en carbones activés et finalement une augmentation de la vitesse de formation et de dépôt du diamant sur le substrat. Reactive atoms traveling faster over a longer trajectory then have a higher probability of collision, which results in an increase in the concentration of activated carbons and ultimately an increase in the rate of formation and deposition of the diamond on the substrate.
Un aimant permanent a été ici décrit, mais toute forme d'aimant, permanent ou non, permettant de générer un champ magnétique approprié dans le voisinage du substrat peut être utilisé.  A permanent magnet has been described here, but any form of magnet, permanent or not, making it possible to generate an appropriate magnetic field in the vicinity of the substrate can be used.
La distance entre l'anode et le substrat/cathode peut être ajustée pour optimiser le dépôt.  The distance between the anode and the substrate / cathode can be adjusted to optimize the deposition.
Ainsi, les trois éléments de l'invention : les moyens de compression du plasma, l'hybridation des sources de courant et l'application d'un champ magnétique dans le voisinage du substrat, ont chacun, séparément, un effet positif sur la vitesse de formation et de déposition de diamant, liant ces trois éléments par un concept inventif unique. Cet effet est d'autant plus prononcé que deux de ces moyens, ou les trois moyens sont utilisés en combinaison, comme illustré dans l'exemple suivant.  Thus, the three elements of the invention: the plasma compression means, the hybridization of the current sources and the application of a magnetic field in the vicinity of the substrate, each have, separately, a positive effect on the speed. diamond formation and deposition, linking these three elements by a unique inventive concept. This effect is all the more pronounced as two of these means, or the three means are used in combination, as illustrated in the following example.
Comme décrit plus haut, les UVC générés in situ dans le plasma concourent à améliorer l'efficacité de la réaction, en favorisant la dissociation des liaisons des réactifs pour former le plasma. Il est également envisageable, pour le même effet de places d'appliquer des UVC à proximité du substrat, là où se forme le plasma. Des lampes UVC peuvent être agencées dans la chambre de déposition chimique en phase vapeur. As described above, the UVCs generated in situ in the plasma contribute to improving the efficiency of the reaction, by promoting the dissociation of the reagent bonds to form the plasma. It is also possible, for the same effect of places to apply UVC near the substrate, where the plasma is formed. UVC lamps can be arranged in the chemical vapor deposition chamber.
De même, pour améliorer encore l'efficacité de la réaction de synthèse, en en particulier la spécificité de cette réaction, les principes décrits dans WO2017121892 peuvent être appliquée. En particulier, des photons de fréquence et/ou d'énergies particulières, choisies pour correspondre à une fréquence d'absorption de la matière à synthétiser et/ou d'un réactif, peuvent être envoyés vers le substrat pour améliorer la vitesse de formation de la matière.  Similarly, to further improve the efficiency of the synthesis reaction, in particular the specificity of this reaction, the principles described in WO2017121892 can be applied. In particular, photons of frequency and / or particular energies, chosen to correspond to an absorption frequency of the material to be synthesized and / or of a reagent, can be sent to the substrate to improve the rate of formation of matter.
Exemple Example
Une chambre CVD de 260 mm de diamètre et 160 mm de hauteur contient une anode en tungstène de 3.2 mm de diamètre placée à environ 35 mm au-dessus d'un substrat en silicium de 15 mm sur 15 mm formant la cathode. A 260 mm diameter and 160 mm high CVD chamber contains a 3.2 mm diameter tungsten anode placed approximately 35 mm above a 15 mm by 15 mm silicon substrate forming the cathode.
Pour les cas où une grille est utilisée, la grille est en molybdène et a un diamètre de 5 cm de diamètre, une hauteur d'environ 1 cm et un maillage de 1 mm.  For cases where a grid is used, the grid is made of molybdenum and has a diameter of 5 cm in diameter, a height of about 1 cm and a mesh of 1 mm.
Pour les cas où un aimant est utilisé, un champ magnétique transversal de 0.02 T est produit par un électro-aimant.  For cases where a magnet is used, a transverse magnetic field of 0.02 T is produced by an electromagnet.
Lorsqu'une source d'énergie hybride DC/RF est utilisée, les deux sources sont ici appliquées en même temps sur toute la durée du dépôt.  When a hybrid DC / RF energy source is used, the two sources are applied here at the same time over the entire duration of the deposition.
Le gaz porteur de carbone introduit dans la chambre est constitué d'un mélange de 3% de méthane dans 97% d'hydrogène. La pression est portée à environ 300 mBar et stabilisée afin d'assurer la stabilité du plasma.  The carbon-bearing gas introduced into the chamber consists of a mixture of 3% methane in 97% hydrogen. The pressure is brought to approximately 300 mBar and stabilized in order to ensure the stability of the plasma.
La température dans la chambre au cours de la synthèse est d'environ 950 °C, ce qui correspond ici à la température optimale de dépôt sur un substrat de silicium.  The temperature in the chamber during the synthesis is approximately 950 ° C., which here corresponds to the optimal temperature for deposition on a silicon substrate.
Le courant continu appliqué est un courant continu de 735 V, d'une puissance d'environ 1200 W (± 100W).  The direct current applied is a direct current of 735 V, with a power of approximately 1200 W (± 100W).
Plusieurs dépôts de diamants ont été réalisés, avec ou sans grille, en appliquant un courant continu ou un courant hybride DC/RF, avec ou sans aimant placé sous le substrat, pendant lh. Les résultats sont donnés dans le tableau ci-dessous :
Figure imgf000015_0001
Several diamond deposits were made, with or without a grid, by applying a direct current or a hybrid DC / RF current, with or without a magnet placed under the substrate, for 1 hour. The results are given in the table below:
Figure imgf000015_0001
La simple présence de la grille permet de doubler la vitesse de déposition et d'homogénéiser la nature du film. La combinaison de la grille et de la source d'énergie hybride DC/RF permet d'accélérer plus de six fois la vitesse de dépôt. The simple presence of the grid makes it possible to double the speed of deposition and to homogenize the nature of the film. The combination of the grid and the hybrid DC / RF power source accelerates more than six times the deposition rate.
Le champ magnétique appliqué ici permet d'éviter les décharges provenant d'arcs électriques ponctuels et conduisant à la présence de trous dans le dépôt de diamant et permet également à lui seul de quasiment doubler la vitesse de dépôt. The magnetic field applied here makes it possible to avoid the discharges coming from specific electric arcs and leading to the presence of holes in the diamond deposit and also by itself alone allows to almost double the speed of deposit.
Des résultats similaires ont été observés pour des substrats en molybdène. La description ci-dessus décrit la synthèse de diamant. Il peut s'agir aussi bien de diamant pur que de diamant dopé avec par exemple des atomes d'azote, afin d'obtenir un diamant présentant des propriétés particulières, comme par exemple les propriétés d'une semi-conducteur. Pour cela, un gaz approprié, en quantité appropriée, peut être introduit dans la chambre de déposition.  Similar results have been observed for molybdenum substrates. The above description describes diamond synthesis. It can be both pure diamond and diamond doped with, for example, nitrogen atoms, in order to obtain a diamond exhibiting particular properties, such as, for example, the properties of a semiconductor. For this, a suitable gas, in an appropriate quantity, can be introduced into the deposition chamber.
II a également été observé, de façon surprenante, que la nature du substrat influence la forme cristalline du diamant, selon qu'il soit, par exemple en silicium, molybdène, tungstène, titane ou quartz. It has also been observed, surprisingly, that the nature of the substrate influences the crystal form of the diamond, depending on whether it is, for example made of silicon, molybdenum, tungsten, titanium or quartz.
Bien que l'intérêt du procédé soit ici démontré pour la synthèse du diamant, les moyens de compression de plasma peuvent être appliqués à n'importe quel autre type de synthèse par dépôt chimique en phase vapeur, à pression atmosphérique ou à basse pression, afin d'en améliorer la vitesse de déposition. Il en est de même pour l'hybridation DC/RF et/ou l'application d'un champ magnétique à proximité du substrat. Although the advantage of the process is demonstrated here for the synthesis of diamond, the plasma compression means can be applied to any other type of synthesis by chemical vapor deposition, at atmospheric pressure or at low pressure, in order to to improve the speed of deposition. It is the same for DC / RF hybridization and / or the application of a magnetic field near the substrate.

Claims

Revendications claims
1. Procédé de synthèse d'une matière, dans une chambre de déposition chimique en phase vapeur et sur un substrat de synthèse, entre deux électrodes de génération de plasma, selon lequel :  1. A process for the synthesis of a material, in a chemical vapor deposition chamber and on a synthesis substrate, between two plasma generation electrodes, according to which:
on introduit dans la chambre un gaz porteur d'atomes de la matière à synthétiser et  a gas carrying atoms of the material to be synthesized is introduced into the chamber and
on créé un plasma à proximité du substrat pour activer des atomes du gaz porteur d'atomes de la matière à synthétiser,  a plasma is created near the substrate to activate atoms of the gas carrying atoms of the material to be synthesized,
procédé caractérisé par le fait qu'on comprime le plasma pour augmenter, à proximité du substrat, la densité volumique des atomes activés et donc la vitesse de déposition de la matière à synthétiser. process characterized by the fact that the plasma is compressed to increase, near the substrate, the volume density of the activated atoms and therefore the rate of deposition of the material to be synthesized.
2. Procédé selon la revendication 1, selon lequel on crée le plasma par application, entre les deux électrodes, d'un courant continu (DC) et d'un courant alternatif à fréquence radio (RF).  2. Method according to claim 1, according to which the plasma is created by applying, between the two electrodes, a direct current (DC) and an alternating current at radio frequency (RF).
3. Procédé de synthèse d'une matière, dans une chambre de déposition chimique en phase vapeur et sur un substrat de synthèse, entre deux électrodes de génération de plasma, selon lequel :  3. Method for synthesizing a material, in a chemical vapor deposition chamber and on a synthesis substrate, between two plasma generation electrodes, according to which:
on introduit dans la chambre un gaz porteur d'atomes de la matière à synthétiser et  a gas carrying atoms of the material to be synthesized is introduced into the chamber and
on créé un plasma à proximité du substrat pour activer des atomes du gaz porteur d'atomes de la matière à synthétiser,  a plasma is created near the substrate to activate atoms of the gas carrying atoms of the material to be synthesized,
procédé caractérisé par le fait qu'on crée le plasma par application, entre les deux électrodes, d'un courant continu (DC) et d'un courant alternatif à fréquence radio (RF).process characterized by the fact that the plasma is created by applying, between the two electrodes, a direct current (DC) and an alternating current at radio frequency (RF).
4. Procédé selon l'une des revendications 1 à 3, selon lequel 4. Method according to one of claims 1 to 3, according to which
- on applique, à proximité du substrat, un champ magnétique.  - a magnetic field is applied near the substrate.
5. Procédé selon l'une des revendications 1 à 4, dans lequel la matière à synthétiser est du diamant, le gaz porteur d'atomes de la matière à synthétiser est un gaz porteur d'atomes de carbone et  5. Method according to one of claims 1 to 4, in which the material to be synthesized is diamond, the gas carrying atoms of the material to be synthesized is a gas carrying carbon atoms and
on créé un plasma (28) à proximité du substrat pour générer des atomes de carbone réactifs. a plasma (28) is created near the substrate to generate reactive carbon atoms.
6. Procédé selon la revendication 2, selon lequel le ratio DC/RF est modulable au cours de la synthèse. 6. Method according to claim 2, according to which the DC / RF ratio is adjustable during the synthesis.
7. Chambre (1) de déposition chimique en phase vapeur, pour la mise en œuvre du procédé de la revendication 1, pourvue d'une entrée (2) de gaz et d'une sortie (3) de gaz, et à l'intérieur de laquelle sont agencées deux électrodes (4, 5) de génération de plasma (28) reliées à une source (6) de courant continu (DC), caractérisée par le fait que des moyens (20) de compression de plasma sont fournis entre les deux électrodes (4, 5).  7. Chamber (1) of chemical vapor deposition, for the implementation of the method of claim 1, provided with a gas inlet (2) and a gas outlet (3), and at the inside of which are arranged two plasma generation electrodes (4, 5) (28) connected to a source (6) of direct current (DC), characterized in that means (20) for plasma compression are provided between the two electrodes (4, 5).
8. Chambre selon la revendication 7, dans laquelle les deux électrodes (4, 5) sont reliées à une source (46) de courant alternatif à fréquence radio (RF).  8. Chamber according to claim 7, wherein the two electrodes (4, 5) are connected to a source (46) of alternating current at radio frequency (RF).
9. Chambre selon l'une des revendications 7 et 8, dans laquelle les deux électrodes sont une anode (4) et une cathode (5), la cathode formant un substrat (5) de déposition de diamant (45).  9. Chamber according to one of claims 7 and 8, wherein the two electrodes are an anode (4) and a cathode (5), the cathode forming a substrate (5) for depositing diamond (45).
10. Chambre selon l'une des revendications 7 à 9, comprenant des moyens (50) de génération d'un champ magnétique à proximité du substrat (5).  10. Chamber according to one of claims 7 to 9, comprising means (50) for generating a magnetic field near the substrate (5).
PCT/EP2019/066079 2018-07-05 2019-06-18 Method and device for diamond synthesis by cvd WO2020007605A1 (en)

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